Mobile Solar Module Testing Vans have Higher Uncertainty of Measurement: TUV Rheinland

These vans are not suitable to make a claim of real power versus purchased power, opined Joerg Althaus, Regional Field Manager of Solar at TUV Rhineland in an interview

September 18, 2018


Recently, Mercom reported on the lack of testing centers in the country with the rapid expansion of the domestic renewable industry. Conversations with various project developers and manufacturers in the country reveal that the announced National Lab Policy and Quality Control Order is adding a new wrinkle that could slow down project commissioning.

To gain more clarity on this story, Mercom India’s news team sat down with Joerg Althaus, Regional Field Manager Solar – India, Middle East, Africa and Germany,TUV Rheinland, to discuss the implications of the government order. TUV Rheinland has its head office in Bangalore, India.

How do the testing procedures work for a solar project?

Usually the contract between developer defines certain tests to be done mostly on modules, but also on other components. Sometimes the lender or owner also has testing requirements.

What are the kinds of tests performed at different stages of execution?

Typically, factory audits and pre-shipment inspections are part of the program. With PV modules, a random sample (depending on the MW size) is usually sent to a third-party lab for testing. Module testing includes: measurement of power, determination of light induced degradation, check of potential induced degradation, documentation of the electroluminescence image, infrared analysis, gel content control, and even a peel off test (the adhesion strength of lamination).

What do you think of mobile testing vans and the like?

Mobile testing vans have a higher uncertainty of the measurement, and hence are not suitable to make a claim of real power versus purchased power (uncertainty usually > 5%). However, mobile devices are suitable for comparative testing to identify if some modules have major variation to others which can indicate a problem. Subsequently, such modules would be sent to a lab.

Yet, making these measurements in the field is actually too late, because modules will not be sent back once they are installed. Alternatively, a sample should be taken before the modules leave the factory, and then sent to a lab for precision measurements. Additionally, measurements in the field are always open to discussion, as modules might have been damaged due to improper handling in the field.

Any comments on new standards (BIS certification, lab testing) by government and how it would help the industry?

Most of the modules manufactured are qualified as per the listed International Electrotechnical Commission (IEC) standards (IEC 61215:2005, IEC 61730-1&2:2007) which are also the adopted standards of BIS. This will help end users avoid the usage of substandard products, which are presently available in the market. However, IEC updated its standards in 2016, so the export market may have different requirements than the domestic market, which means more effort for the manufacturers.

What are the common issues faced during the testing phase? And how can the industry overcome them?

Recently, we have identified problems with back sheets (such as brittleness, discoloring). In the past, PID (potential induced degradation) was the biggest problem, which has been overcome. However, it may resurface with new technologies and new higher system voltages. Regular and random testing imposed by buyers will be needed to improve quality. We must also be aware that a price decline sometimes means previously conducted QA measures have been lifted. In summary: Prevention is better and cheaper than the cure…………………

Will TUV certify MNRE’s BIS Quality Order?

Yes, we can test and issue reports according to IS 14286, IS/IEC 61730-1&2

What is the cost of testing for a MW-scale solar project?

As per the requirement of BIS under the existing CRS scheme, we need to test and issue reports for PV modules, inverters and batteries. They can use multiple brands which are qualified as per BIS requirements in MW-scale plants. The cost purely depends on product and its set of components used.